The charred remains of six people have been discovered in California as thousands of evacuees start returning home after what have been described as the most devastating wildfires in the state's history.

Four of the victims, believed to be three men and one woman, were found yesterday afternoon in scorched woodland along the Mexican border south-east of San Diego. The area is near a key corridor for illegal immigrants coming from Mexico.

Two more bodies, a man and a woman, were uncovered in the rubble of a burned house in the town of Escondido in San Diego county. It was reported they had been urged to evacuate but refused.

The discoveries brought the official death toll to seven after a 52-year-old man was killed on Sunday. A suspected arsonist, Russell Lane Daves, 27, was shot dead by police on Tuesday near San Bernardino university.

Firefighters have taken advantage of much gentler winds and lower temperatures to launch an aerial bombardment of some of the largest blazes still burning, although some fires in San Diego county and Lake Arrowhead are still only 30% contained.

The fires have destroyed 1,500 homes, displaced half a million people and caused damage worth an estimated $1bn. Five people in San Diego, San Bernardino and Los Angeles counties have been arrested on suspicion of arson, although the police said none had been linked to any of the major fires.

Across many affected areas, mandatory evacuation orders were lifted yesterday and residents returned to a blackened landscape.

In San Diego county, sheriff Bill Kolender said several confrontations had arisen between police trying to manage the return and residents trying to get back to their neighbourhoods as soon as possible.

"In some areas, particularly Ramona, some of the residents have become quite angry, and they have driven a car into one of our law enforcement vehicles," he said at a news conference.

The US president, George Bush, yesterday visited areas devastated by the fires, promising swift and generous government aid to those who lost their homes and livelihoods to the flames.

The four-hour tour began with a helicopter trip over charred hills and included a brief visit to a gutted home in the San Diego neighbourhood of Rancho Bernardo. It was intended to innoculate the administration from a repeat of the criticism that followed Hurricane Katrina.

"I want to let people know out here in southern California that many across our nation have been moved by the plight of citizens who have lost their homes, lost their possessions, and particularly those who have lost their life," Mr Bush said. "I've come to make sure that the federal government provides help for people here at the local level."

His effort to demonstrate a prompt and caring response to the disaster was backed up by the state's governor, Arnold Schwarzenegger, who said the White House had offered support before he had a chance to ask for it. "I call this quick action - quicker than I expected, I can tell you that," Mr Schwarzenegger told reporters.

Yesterday's visit was choreographed between the White House and the governor to ensure Mr Bush conveyed an impression of concern, without being accused of hindering the relief effort with a presidential visit.

The administration had declared the fires a major disaster on Wednesday, a step which allows federal relief agencies to funnel more assistance.

However, Mr Bush faced accusations of trying to score political points from the misery of others, and Democratic leaders said the Iraq war had drained resources which could have gone towards preventing and fighting fires.

"We'll be polite, but frankly that's not a solution," California's Democratic lieutenant governor, John Garamendi, said on the eve of the presidential visit. "How about sending the national guard back from Iraq?"

The fires also disrupted the lives of those ordinarily insulated from natural disaster by their wealth and connections. Many Hollywood celebrities maintain second homes in the Malibu area. Others frequent its sushi bars and even rehab clinics such as Promises, where Britney Spears and Lindsey Lohan were treated and which was evacuated.

Olivia Newton-John, who starred opposite John Travolta in the film Grease, was among the first to be evacuated at the weekend as hotels in beachfront towns filled up with well-heeled refugees from the flames. Cher and Mel Gibson also had to flee to safety.

Several of the evacuees have moved into the notorious celebrity hangout Chateau Marmont. For those unable to pay for such exclusive refuges, the billionaire record producer David Geffen invited firefighters and volunteer workers yesterday to stay for free in his recently renovated Malibu hotel.